Refrigerating apparatus



Nov. 16, 1943.

L. A. PHILIPP REFRIGERATING APPARATUS Filed April 12, 1941 error/15v P. .P 6 I 1 ml, 6 m4 4 m 0 VP 4 2/ m l w. 4, 1 w 0 I. w w m 6 H w n a a. L .J m 1 1J 0 a /v u f 0 a 4 6 F 8 dd; H l 6 M Z m 7; Z 2 aw Patented Nov. 16, 1943 Lawrence A.

rmup Detroit, Mich, assignol' to Nash-Kelvinator Corporation, Detroit,fMich., a corporation of Maryland Application April 12, 1941, Serial No. 388,252

Claims.

This invention relates to refrigerating apparatus, and, particularly, to refrigerating apparatus ofthe household type.

In accordance with my invention I have pro- One of the objectspf my invention is to pro-" vide an improved cooling unit in a refrigerator cabinet for freezing purposes and for cooling the circulating air within said cabinet without the collection of frost on said unit.

Another object of my invention is to provide an improved cooling unit in a refrigerator cabinet comprising a low'temperature refrigerant. evaporating element supported. within a metallic casing in heat conducting relation therewith, with the casing being provided with an extended outer surface of such area that while freezing temperatures are maintained within the casing, nonfrosting temperatures-are maintained at the outer surface for cooling the circulating air within the cabinet.

Another object of my invention is to provide an improved cooling unit in a refrigerator cabinet comprising a low temperature refrigerant evapcrating element for freezing purposes and a metallic casing arranged to isolate said evaporating element from direct contact with the circulating air in said cabinet, said casing being provided with this which are constructed integrally with the casing itself and which extend outwardly into the path of the circulating air in the cabinet to thereby provide large extended surfaces for ylded an improved cooling unit for freezing purposes and for cooling circulating air without collecting frost thereon at least part of the time. This unit comprises a metal casing provided with "a large extended outer surface and a low temperature refrigerant evaporating element supported within cooling the circulating air with the collection of little or no frost thereon while freezing temperatures are being maintained insidethe casing.

Another object is to provide an improved cooling unit for refrigerators which will operate to maintain a plurality of temperatures economically and one which can be readily manufactured atlow cost.

Further objects and advantages of the present invention will be apparent from the following description, reference being'had to the accompanying drawing, wherein a preferred form of the present invention is clearly shown.

In the drawing: i

Fig. 11s a front view in elevation, partly broken away, of a refrigerating apparatus embodying features of my invention;

Fig. 2 is a view-in cross section,'taken along the line 2 2 of Fig. 1, witha diagrammatic illustration of the refrigerant condensing element removed from the cabinet;

Fig. 3 is a view taken along the lines Fig. 2; and

Fig. 4 is a view Fig. 2.

taken along the lines 4-4 of to the refrigerant evaporating element. the rather limited path of conduction and due to the eflectivenessof the extended surface of absorbing area that the .disposed a refrigerant evaporating the casing by metal shelves extending between the walls of the casing in direct contact therewith. The extended outer surface of the casing is preferably obtained by bending the sheet metal back upon itself for forming outwardly facing fins in the walls of the casing itself.- This extended outer surface serves to absorb a large quantity of heat from the circulating air within the cabinet. This heat is transferred by conduction through the casing Due to the casing in absorbing heat, a temperature differential is established between the temperature of the outer surface and the temperature of the evaporating element. The differential will depend upon the extent of the outer surface, the more extended it is, the greater. the differential, and vice versa. While the low temperature refrigerant evaporating element within the casing is adapted to maintain the metal shelves therein at freezing temperatures, I provide the casing with an external surfaceof such a large heat temperature of the outer surface is maintained at least part of the time above the frosting point. This unit can be .manufactured readily and at low cost since it can be .made entirely of thin sheet metal material and .only simple operations are required to form it The cabinet 20 is provided with a food storage compartment 32. t

Withinthe cabinet adjacent the top wall 22 and midway between the side walls 26 there is element 34. The element 34 includes a metallic casing 36 preferably formed of thin sheet metal which is supported from the top wall 22 by means of supporting brackets 38. Within the casingis disand metal shelves posed a refrigerant coil or heat absorbing means 39. This casing serves to isolate the coil 39 from direct contact with the circulating air in the food storage compartment 32. The two side walls 40 of the casing 36 are provided with fin-like projections 42. Accessto the interior of the casing is gained by means of a door 44 located in the front wall 46 of the casing. 1

The interior of the casing 36 isfdivided into several small compartments by means of shelves 50 which are fastened by some suitable means, such as rivets 62, to the side walls of the casing. These shelves are adapted to support pans in which water and desserts are to be frozen. The refrigerant evaporating coil 39 consists of asuccession of conduits or coils 64, one beneath each shelf, each coil being connected to the one immediately above by conduits 66. If desired, instead of conduits 64 a sheet metal plate may be embossed to form serpentine passages and sea cured to the shelves to form the evaporating element. Disposed near the rear of the casing 36 behind the shelves 60 is a tank 66 which is .in

with the refrigerant coil open communication 39 at points 10 and 12 located at the top and bottom, respectively, of said tank. The tank 68 is supplied with liquidrefrigerant by means of a condensing unit 60 which is located outside the food compartment, preferably in a special machine compartment. .The condensing unit comprises, in general, a compressor 82 driven by a motor 84, and a condenser 86. The compressor 82 compresses refrigerant vapor and forces the compressed gas into a condenser 86 wherein it is liquefied. The liquid refrigerant is conducted to the tank 68 through a supply conduit 86 under the control of a float valve 90. A conduit 92 serves to return vapor from the top of the tank 60 to the suction side of the compressor. The operation of the condensing unit 80 is controlled by a thermostat 93 which includes bulb 94 disposed on the side wall of the casing 40 and operatively connected to the motor 84 of the condensing unit. In order to increase the heat absorbing qualities of the metallic casing 36 to such an extent that no frost will collect upon the casing, or so little collects that it will melt during the off phase of the condensing unit, I have provided the casing with fins 42 formed from the casing itself. The side walls 40 of the casing may consist of a continuous sheet of metal with U-shaped bends in the sheet formed by bending the sheet backupon itself at regular intervals forming fin-like projections which extend from the top to the bottom of the casing as shown in Figs. 3 and 4. Or, on the other hand, the side walls 40 may not consist of a single continuous sheet of metal but may instead consist of a number of separate sheets bends or fins in it, all

each with one or more U the separate sheets being riveted together to form a wall of the casing. In either case, the result of putting all these U bends in the metallic wall of the casing is to present a much larger'surface of heat absorbing material to the circulating air in the food storage compartment than if a flat sheet of metal were utilized.

The operation of my improved refrigerating apparatus is as follows:

When sufiicient liquid refrigerant has entered the casing I from the condenser 96, the float 90 rises lifting the valve proper I02 from its seat I04 and allows refrigerant to fiow into the conduit 86. The conduit 83 terminates inan ejector sure enters the evaporator 34 I06 which is in open communication with the interior of tank 66 and with the entrance 12 of the evaporator 34. This ejector I06 is tapered and extends into the cone shaped inlet 12. Liquid refrigerant leaving the ejector under presand circulates through the conduits 64 to the top of the casing. Refrigerant vapor and unvaporized liquid enter the tank 68 at near the top thereof. The liquid drops into the tank and is recirculated through the refrigerant conduits 64 by the action of the ejector I06. The ejector also serves to initiate and promote the ebullition of the liquid refrigerant inthe conduit 34 and in the tank 68. 'The vaporized refrigerant is returned from the tank 68 through the conduit 92 to the condensing unit 80. I

During normal operation of my improved refrigerating system the tank 60 is nearly filled with liquid refrigerant. Since said tank is in open communication with both ends of the refrigerant evaporator 39, the evaporator is normally'in a flooded condition. As the liquid refrigerant circulates through the conduits 64 which lie beneath the shelves 60 it absorbs heat therefrom reducing the temperature of the shelves below ing is cooled somewhat by and the like placed in immethe shelves are thus cooled freezing. Ice pans diate contact with below the freezing point of water.

The shelves 60 as previously pointed out are attached to the side walls 40 of the casing 36. The warm circulating air of the food storage compartment 32 continuously contacts the outside surface of the casing 36. Since the shelves are maintained, as we have seen, at a temperature below freezing, there is some fiow of heat from the casing to the shelves and finally to the refrigerant evaporator 34. In addition, the easconvection currents within the casing but this is slight and is further reduced due to the presence of the shelves. In order to prevent the casing itself from being reduced to a temperature below freezing the finlike bends 42 were incorporated in the casing itself to increase the heat absorbing surface thereof. The amount of heat absorbed from the air in the food compartment by said casing refrigerant conduits ing cycle. The amount of frost allowed to collect on the casing may be controlled by the thermostat, by varying the size of the casing or, further, by varying the surface area of the fins. By extending the finned surface, it is possible to practically eliminate the collection of frost on the casing even at the points of contact of the refrigerated shelves and the casing. Reducing the size of the fins will lower the temperature differential between the fins and the refrigerant evaporating unit and will, if reduced sufficiently, lower it to the point where frost will deposit on the surface. I prefer to employ fins of s'uch a size thatfrost does not collect at all orin such limited amount that it will melt off during the ofi-cycle.

The thermo bulb 94 is attached to the side of the casing 36 for controlling the operation of the condensing unit 80. The bulb 94 is filled with fast enough through some temperature responsive fluid and connected to a tube i III which is likewise filled with the same fluid. Some suitable mechanism is disposed in a casing I I2 for utilizing the expansion and contraction of the above mentioned fiuid to make and break an electrical circuit H4. The electrical circuit H4 includes lines H6 and Ill, motor N, and line I20. When the temperature of the easing rises above a predetermined value the fluid in the bulb 94 expands and closes the circuit I. The motor 84 thenstarts and the condensing unit begins to operate. When the temperature drops to a predetermined value, the fluid in bulb N contracts and breaks the circuit Ill. The motor 84 then stops and the condensing unit to ceases to operate. The thermo bulb 04 may be placed, if desired, in any suitable place other than that shown. A hand operated switch in is inserted in the casing H2 for breaking the 'circuit ill when it is'desired to discontinue operation of the refrigerating system.

It is apparent from the foregoing that I have provided a refrigerator comprising two or more compartments, one of which is maintained below freezing, and the others of which are'malntained above freezing without the deposition of frost by means of a heat absorber disposed in the compartment which is kept below freezing. I have accomplished this result by increasing the heat absorbing qualities of the walls separating the freezing compartment from the other compartments to such'an extent that the temperature of said walls does not fall to the freezing point of water. I have thus provided in a refrigerator a high humidity food storage compartment and a low temperature freezing compartment in which i is disposed a singlev refrigerant evaporator, for

maintaining the freezing compartment below freezing and the food storage compartment above freezing with the formation of little or no frost. as desired, in the food storage compartment. Furthermore, I have provided an improved refrigerant evaporating element for maintaining a plurality of temperatures in an economical manner by merely extending the surfaces of an enclosing casing by forming therewith large finned surfaces which enables the operation of my unit for both freezing and air cooling with high humidity in the food storage compartment and defrosting eliminated.

Although only a preferred form of the invention has been illustrated, and that form described in detail, it will be apparent to those. skilled in the art that various modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

I claim:

1. In a refrigerating system, the combination -with a cooling unit comprising a sheet metal casing formed of thin sheet metal walls and havin a plurality of outwardly extending fins associated in intimate heat conducting relation with a plurality of saidvwalls, a plurality of shelves disposed within saidcasing and directly connected to the walls thereof and a low temperature heat absorbing means arranged entirely within said casing in spaced relation to the side walls thereof and in direct heat conducting association with said shelves for maintaining sub-freezing tempera tures within said casing and non-frosting temperatures at least part of the time on the surface of said fins, said fins having an aggregate area such that the heat absorbed from the circulating air prevents a greater amount of frosting from being deposited on the fins than can be frozen during the ofi cycle of the system.

2. In a refrigerating system, the combination with a cooling unit comprising a metal casing formed of thin sheet metal walls, outwardly extending fins constructed integrally in a plurality of said walls, a plurality of thin sheet-metal shelves disposed within said casing and directly connected to the walls thereof, and low temperature heat absorbing means arranged entirely within said casing in spaced relation to the side walls thereof and in direct heat conducting association with said shelves for maintaining subfreezing temperatures within said casing and nonfrosting temperatures at least part of the time at the surface of said fins, said fins having an aggregate area such that the heat absorbed from the circulating air prevents a greater amount of frosting from being deposited on the fins than can be frozen during the of! cycle of the system.

3. A cooling unit for refrigerating apparatus comprising a casing formed of thin sheet metal walls and having a plurality of relatively thick outwardly extending fins associated in intimate heat conducting relation with a plurality of said walls, a plurality of shelves disposed within said casing and directly connected to the walls thereof, and a low temperature refrigerant evaporating conduit arranged entirely within said casing in spaced relation to the side walls thereof and directly secured to said shelves for maintaining sub-freezing temperatures within said casing and non-frosting refrigerating temperatures at least part of the time on the surface of said fins.

4. A cooling unit for refrigerating apparatus comprising a casing formed of thin sheet metal walls, relatively thick outwardly extending fins constructed integrally in a plurality of said walls, a plurality of thin sheet metal shelves disposed within said casing and directly connected to the walls thereof, and a low temperature refrigerant evaporating conduit arranged entirely within said casing in spaced relation to the side walls thereof and directly secured to said shelves for maintaining sub-freezing temperatures within said casing and non-frosting refrigerating temperatures at least part of the time at the surface of said fins.

5. A cooling unit for refrigerating apparatus comprising a casing formed of thin sheet metal walls and having a plurality of outwardly extend- -ing fins associated in intimate heat conductin relation with a plurality of said walls, a plurality of shelves disposed within said casing and directly connected to the walls thereof, a low temperature refrigerant evaporating conduit arranged entirely within said casing in spaced relation to the side walls thereof and directly secured to said shelves, means for delivering liquid refrigerant to said conduit, and means disposed within said casing for re-circulating any unvaporized liquid refrigerant at the outlet of said conduit back through said conduit.

LAWRENCE A. PHILI PP. 

